Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the write-but-non-destructive profile is covered. The description adds one genuinely useful behavioral detail — the created milestone defaults to status 'Open' — but says nothing about permissions, whether attached runs must belong to the project, or what the call returns.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

A single front-loaded sentence stating the core action followed by the optional surface area; no filler and nothing redundant. Appropriate size for a create tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With 8 well-documented parameters, required fields, and annotations covering the safety profile, the description covers enough for correct invocation. It only omits return/ID behavior, which is a minor gap given there is no output schema.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% (owner, dates, tags, test_run_ids all documented in the schema), so the description's paraphrase of those fields adds little. Baseline 3 is appropriate when the schema carries the parameter semantics.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific verb+resource ('Create a milestone in a project') and enumerates the optional payload (description, dates, tags, runs), so it is easily distinguished from siblings like tm_update_milestone and tm_create_project. An agent can identify what the tool produces without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied by the verb 'Create'; there is no explicit when-to-use guidance, no note about prerequisites (e.g., project must exist), and no routing to alternatives such as tm_update_milestone for modifying an existing milestone. Adequate but with clear gaps.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.